The working principle of an oil pumping machine with a sucker rod is pumping petroleum out from an oil well through the vertical up-and-down movement of the sucker rod. An existing oil pumping machine with a sucker rod generally comprises a speed reducer, a balance system, a reversing device and various mechanical driving devices. The energy transfer way of such an existing oil pumping machine with a sucker rod is: electric motor-belt wheel-speed reducer-balance system-reversing device-various mechanical driving devices, etc. There are many transfer links, resulting in high energy consumption and serious waste. During the operating of such oil pumping machines, the work done by the oil pumping machines is not uniform due to their structural features. In the up-and-down stroke of such an oil pumping machine, the energy required by the sucker rod varies greatly, while the output power of the electric motor must correspond to the power required by the movement of the sucker rod. Specifically, the power of the electric motor must meet the maximum power in the up-and-down stroke. Therefore, the installed capacity of the electric motor is large, generally multiple times larger than an actually required average power, and even above 7 times. Meanwhile, due to the starting characteristics of the electric motor, there is a large impact to the power grid, thereby causing serious pollution to the power grid. A Chinese Utility Model CN200982182Y, published on Nov. 28, 2007, disclosed such an oil pumping machine.
Under the condition of on-grid wind power, the energy transfer way of an existing wind power generation system is: wind energy-transmission-generator-controller-converter-power grid-loads; while under the condition of off-grid wind power, the energy transfer way of the existing wind power generation system is: wind energy-transmission-generator-controller-storage batteries-inverter-loads. A considerable part of the captured wind energy will be consumed during the multi-link transfer, resulting in low equipment efficiency. As current flows from high voltage to low voltage only, the output voltage of the electric motor is lower than the voltage of the power grid or storage batteries when the existing wind power is at a wind speed of 3-4 m/s. Although the wind energy can generate electricity, the electricity cannot be utilized. The utilization ratio of wind energy is low. Due to the instability of wind energy, the output current and voltage are instable, and a great impact is thus generated to wind power equipment. As a result, the technical difficulty and failure rate are increased, and the reliability is lowered.